Method for vaporizing liquefied petroleum gas



June 15, 1937. q. w. MARTIN M E'mon Fon vAPoRIzfING LIQUEFIED PETRoL'EUMGAs Filed April 30, 1935 IIIIIIIII'IIIrIIIIlII I/ l//l/Il 1 ll/ Patented .lune 15, 1937 METHOD Fon vAPoRIzING LIQUEFIED PETROLEUM GAS X James Woodward Martin, Dallas, Tex.,'assgn`or to Lone Star- Gas Company, Dallas Tex., aoorporation of Texas Application April so, 1935,- serial No. 19,114

Vs c1aims. (c1. az-211)- My invention consists in new and useful improvements in a method and apparatus forconverting liquid hydrocarbons, such for example as liqueed petroleum'gases, into a gas for useV as 5 domestic and industrial fuel, the present applicationvbeing a continuation in part'oi my co5- pending application Serial No. 731,231, ledJune 19, l1934. l

As in my former application; the'object of the' present invention is to provide na method of vaporizing substantially pure butane and analogous liquefied petroleum gases wherein the rate of vaporization of the liquid is automatically controlled by the rate Aof, consumption'of the gas` formed. A Y

It has-long been known that various 'hydro.Y carbons may be ,stored inthe liquid state and used as fuel upon vaporization. It has likewise been lknown that the latent heat of vaporization 9,0 of the particular hydrocarbon used must be sup` plied to the/liquid hydrocarbon during .the Vvconversionof the latter into the vapor state. Hydrocarbons such as propane which will vaporize at: ,very low temperatures and therefore more readf 'ily absorb thel heat required for vaporization from the atmosphere through the walls of the storage containers, have long been ,used as fuel in liquid'gasjsystems. However, such hydrocarbons lare rather expensive and diicult to obtainV inf1arge quantities andthe expense'o'f handling' 'fthese hydrocarbons in the liquid phase is a con? siderable item because of'their very highu vapor pressures at normal atmospheric temperaturesy which requires heavy andA expensive equipment'to'l Y retain and transport-the liquid. f

Hydrocarbons having lower 40 lighter equipment.

bons for vaporizing Ythe same. For example, this has been effected by exposingthe container in which the hydrocarbon Vis, stored, to-the `vatmosphere or tothe groundjn some'climatesthe atmospheric temperatures nor s ground tempera-,h 5Y tures being sufciently highto producethe-re-x quired amount ofheat yto lvaporize theliquid A 1 hydrocarbon where comparativelyY low rates fof evaporation are required Vand during atleast a few months of the year. Naturally by this procedure there is no'insurance of uniformity in the` production of gasv for fuel use.

In some instances the liquid hydrocarbon has been exposed directly toa liquid of low volatilityand of low solubility in the hydrocarbon, mostcommonly water, the heating liquid havingja is. made directlyl from the heating liquid to the bons vand being caused .to'ow'over the hydrocar-Y temperature higher than the boiling-,point of theY i hydrocarbomin which case the transfer ofV heat hydrocarbon. Also hydrocarbons have beenV ex-V posed indirectly to another liquid such -as water* while said hydrocarbons-Were contained inV Stor-f age vessels, the waterf having a temperature higher than the boiling point of the hydrocar-l bon container or through a tube or coil submerged 'Y j, in thehydrocarbon,v whereby the heat 4of the Water" is i. transferredl Vto the hydrocarbonr in directly throughrthe Walls :ofthe container., or, the tubes;V f" f f In stillrvotherY instances, lsteam* Yhasbeen e`m-y ployed'for indirectly heating liquidhydrocarbonsv tially atmospheric pressure, at temperatures which approach atmospheric temperature, the

latent heat of `vaporization of such hydrocarbons which must be supplied to convert the liquid into must be supplied A-My present"invento'ngv asfthat covered in'myv v co-pending application,` relates to an; improved ,method and apparatus for supplyingrthe required heat Vof vaitiorizationtoV liquid hydrocarbons par ticularly of this character. 1 1 l Ieam familiar withyariousjmetho'ds heretofore ,-,5 employedfor applying heat'to liquid Vhydrocarthermal eiilciency 'has been low .andthe cost l'of operation high. .l f

Vwhile the latter are confined instorage vessels, Vand'in-sorne instances the heat required Vto genl Y i erate the steam or to heat the heating liquid'has vapor VVpressures such as butane'are not only more plentiful' V'and .cheaper toproduce in a state 'of gfsatisfactory pu#Y rity, but they may be fstored asliquids in cheaper,`

y However, valthough suche` hydrocarbons as butane4 vaporize under substan-y been derived fromthe combustion vof a portionY Q, of the hydrocarbonvapors formed. A In1allof these former methodshoweventhe It is the primary object olf. my invention to 'overcome the diiiiculties andy disadvantages inutilization by maintaining the entire volume of stored liquid hydrocarbon at suchtemperature as will produce and maintain under service conditions an adequate vapor pressure. Ifpermit thev hydrocarbon to pass from the storage con- 'tainer for purposes oi' utilization only as a dry VventionV consists inthe novel features herein Aset forth, illustrated in the accompanying drawing I so l Y :i5

- revaporizing conduit.

vapor o! which there is -a constant ready supply regardless of atmospheric or` groundconditions.

With the above andlother objects in view which will appear as the. description proceeds, myeinf and more particularly pointed out. in the apr pendedclaims. Y "Referring kto the drawing'lnwhich numerals of like character designatesimilar partsthroughout both views, .i

Fig. 1 is a vertic sectional view shoilivingy a storage container equipped with one` form o! heating means similar to that covered in my copending'application hereinbefore mentioned.. and Fig. 2 is a similar view showing a modified i'orm o! heating means.

Both of these figures illustrate my In the drawing, I represents asuitabie storage vessel preferably insulatedito reducetoa practical minimum the transfer of .heat betweenV the:A container and the' atmosphere.- 1 is an inlet confA nection located at any suitable `point in the wall of the container and through which the supply o!Y liquefied petroleum gasV is4 charged to ,the ref-.-

` ceptacle, said connection being provided withany conventional valve means. Y 'In the'top wall of the container l, I provide a valved vapor outlet 3 to 'which-is connected a vapor `line l, the latter havingrinterposed therein a conventional.-.gasY

regulator; ffor maintaining on the serviceline l V line 8 to the burner'l is -a'iitorxiatically` controlled'- fiacle .finto me liquid downwardlyat-an. 1

a reasomibiyg constant pressurelv of.; any Y.desired value less than'. pressureV in fthe storage? contai ner.. Y Y* 1...'.4 v 1 Referring to Pig."-1,. `lzreprescnts a oi.' any suitabletype locatedinsubst'antially closeYV proximity to'jaiportion tof theI :iottom wall of the container l, said burnerbei'ng'ffedby .a :branch lineB leading from the service"line' .Sjand prok vided with a valve 9. The flow: of `gas through bya pressure actuatedr valve I0 which is' re.

sponsive `to the pressure'in the vapor space above theliquid in cofntainer` |,by means lof a'conduit Il connected to the vapor line l at ajp'oint'anterior to the regulator 5L A second branch line I2 fleads from branch line 8` tol a pilot 'I3 immediatelyadjacentthe burner 1, theflowof gasto said pilot=beingxcon trolled by asuitable valve i4;

Directly above the 4burner I lathe mouth "l5 of' a heattransfer element I8 .which consists offV a tubular conduiftgextendingvertically fora short f distance *through th bottomfgwallf of theirecep said receptacle end then clined portion extending",- i

i vice I9 arrangedadjacent thejiviill'oi! the improved n storage receptacle must be somewhat greater.

contained vvin the receptacle.. The discharge end ofconduit 6' projects through the oppomte wall of the receptacle where'it is adapted to beacon# nected to kthe distributing system of a houseor other Vplace ofk utilization. a Y In the'top wall of the receptacle i,.I-` preferably installapressure relief; valve I l tofprevent cessivepressures .in the storage by exhausting the high pressurevapors to thiiaiz-y mosphere kwhen the.4 pressure in the receptacle., f reaches a predetermined amount.'V .'A gaugingdec tacle permitsready determination lof the 1 liquid u content so that the liquidmaybe replenished before :the supply in the'storage receptacle comesexhausted. f j Referring to Fig.' 2, it will be' ot the details of structure arc.idc nti calfwith just .described with the that for the submerged heattran'sferelement I., in Vthe modied form I providelacoil I lhwhichis f` connectedto `v`th side willig!V thestorage time i. Ahum r 1an the lower .extremity of the'coll 2l andisfed pipe la from the service 0.'. "als "cated immediately burner .'I and k,is fed by pipe llarbranchlotl' of pipe ving thus de ribed the construction oranparatushy means of which my improvedmethod lmay be carriedout,y itsoperation is as follows: rvl'ieferringto Fig. 1,.liquidhutaneor is introduced into theftankor' receptacle I' through thevalved inletl. leavingfa'vapor space p above the liquidlevel, which with hydrocarbonlgas. Naturally,`,iffthisg as vapor is to be use'd as fuelin any. ordi ofggas burner, the pressuredn atmospheric` pressure. so that-.the vapor will now from the ftanbto the burner. and under comeY conditions.: for example in weathcrr Vcient heat is absorbed. from supply thenecessary vapor pressureand'the va-l irpors formed in the space aboveftheliquid level cial heatingffmeans .is necessary. 'I Jnder thesa.VVA f conditions, the pilot Iisfr'llghted afterfirstopening valves9 and", the alnburnerlbeing no 1- lmally shut oilv by pressu control valvell w ,en ff thevvaporfpressure in tanv isabovea rc te constant supply of fuel vapor. The fuel con-V sumesfa certain quantity of heat. the

removalof "Vapor from the tank cause-s ar de-V crease in the temperature of the liquid in the tank, and as the liquid becomes cooler, its vapor pressure in turn decreases. i

When the vapor pressure in the tank has fallen below apredetermined value, the pressure controlled valve I0 opens in response and' permits the flow of gas from the service line 6 through 10 pipe 8 to the burner 1 which is-ignited by'thepilot I3. The products oflcombustion from thek burner'l pass upwardly through the mouth I5 I have described two forms of apparatus by charged at the outlet end I1 of the latter. The

of the heat transfer element a I6 and are disheat transfer element I6 beinglsubmerged in the liquid in the bottom of tankl raises the temperature of said liquid and in turn increases the vapor pressure in the space above the liquid, and after' this vapor pressure hasbeen brought up to the 2O proper Value, the valve l0 automatically shuts off the supply of gas to the burner 1, the pilot remaining lighted.

It will be noted that the angle of inclination of the major portion of the heat transfer line I6 permits any water of condensation to drain towards the discharge end, thus conducting any4 duit and is immediately revaporized due to the l heat exchange between thellquid hydrocarbon in the container and the conduit 6. As before stated, this conduit 6 is located in the lower part ofthe storage receptacle so that even when the liquid in the receptacle is at a low level, this desired heat exchange is elected.

' Byllaying the distribution or house piping (not shown) to grade so that the lowermostpoint in the curved conduit 6'is the lowest point in the entire vapor line, any condensed vapors that may form in the house piping will flow towards this low point and .upon reaching that portion of the conduitl which is submerged in the storage container will become re-heated, and if condensation of vapors in the `house piping reaches the liquecation state, such liquid will become revaporized upon reaching conduit 6'. Thus by re-heating or revaporizing these vapors before passing into the house piping, a more uniform vapor temperature and burner performance is insured.

The operation of themodifiedform of my invention shown in Fig. 2 embodies the same principle as that just described. However, instead of heating the liquid by passing the products of combustion through a conduit submerged in said liquid, in the modified form the heat is applied by burner 1a to the coil 30, vaporizing the liquid in the coil and causing a circulation from the tank through the coil and back tothe tank. This circulation gradually heats the entire body of G5 liquidin the receptacle to a suicientnegree to maintain the required vapor Vpressure for distribution of the fuel through the service system. The automatic control and the re-heating or revaporizing features in the modified form areidentical with those heretofore described.

It will thus be seen that I have provided an improved methodv and apparatus which may be readily and economically employed inV connection with distribution systems for liquefied petroleuin gases to insure at allV times a ready and sumed by the heating burner and the pilot is only a fraction of the total fuel vaporized, andvention may be readily understood by those skilled in the art without further description,it being borne in mind thatnurnerous changes may be l'made in the details disclosed without depart-4 ing from the spirit of my invention aft set forth in the -followin-g claims. For example,'although means of whichmy method may be carried out.'

tion isneither limited to apparatus shown and described nor to the use of butane'.` Obviously* this invention may be practiced withany of the liquefied petroleum gases. WhatV I claim and desire to secure by Letters Patent is:-

1. A method for converting liquefied Ypetroleum gas into vapor for use as fuel, consisting in maintaining a body of the liquid in a storage zone,

maintaining a vapor space above the level of said liquid, conducting heated products of combustion of a portion of the effluent vapors into close proximity with said body of liquid but .out of contact therewith to vaporize the same, and maintaining the vapors thereby formed in a vapor state by conducting said vapors through said heated body of liquid but out of contact there-V ing said bulk lsupply by directing the products of said combustion through a passageway submerged in the liquid confined in said storage zone, and conducting the remainder of said vaporsl through a passageway submerged in the,

liquid `confined in saidY storage zone, thus utilizing'the heat contained in said liquid for maintaining said vapors in a vapor state.,

3. A method of converting liquefledrpetroleum Y n gases into a gas `for.use as fuel, consisting in maintaining a bulk supply of the liquid inea 'burned as required to maintain a predetermined pressure in saidstorage zone, controlling the increased fiow of vapo-rs above the predetermined minimum required,*by the vapor pressure in said zone, and heating said bulk supply: by directing the products of Vsaid ,combustion through a passageway submerged in the liquid confined in said storage zone.

4. A method of converting liqueed petroleum gases into gas for use asfuel, consisting in maintaining a bulk supply of the liquid-,in a storage zone, maintaining a vapor space above the level of said liquid, vaporizing a. portion of said liquid,

burning a portion only of the vapors formed,'in closeproximity to the liquid in said zone, heating said bulk supply by the kheat of said combustion while the liquid is confined inV said storage zone,

and conducting the remainder of said vapors Y through a passagewayy submerged inthe liquid in V'said .zone, thus utilizing the heat contained in said liquid for maintainingY said Yvapors ix a `vapor state. Y l Y Y Y 5; YA method of convertingv liqueed petroleum Y 5V gases. into gasrforuse a'siuel, consisting in main- Y Y taining a. bulkjsupply oftheliquid in a storage v Vzone, vaporizing a portion of saidllquid, burning i j" aportion off the vapors formed, vanclconducting Va restrictedstream.r of said liquid from s'aid'bulk m supply, through the vproducts of combustion from *l said burning step, butout o1' contact therewith,

` and baclnto said bulk supply to Yheat ,theV latter. f 6. A method asV claimed in claim 5 Lwherein the remainderl of said vapors formed. in salid `V 1 iistorage zone are-conducted-through Yarpassage-k Y way Vsubmerged in the liquid in saidf zone,thus` ucuizing the neat Vcontained in sindk liquid for Y maintaining said vapors Vin Ya.va.p'or` state. s

' A-method of convertingsliqueed petroleum 2'0ugase`s into a, gas for usegrasrfuel, consisting in maintainingatbodyA of the liquid {n.arstorage zone, maintaining a vapor spa'ceabpve 'the' level of said liquid. vaporizing'a. portion'of salid liquid t within said zone,V conductingrsaid vapors said zone through a. -passagewysplittmginldi se vapors into twostreams. the vapors'o! one stream'jat apoint infclosefproximity to the` lower extrentyoirsaid storge zonetiiereiw forming hot products of combustion; conductin 'Y thevpo-rs 'of the otherf'strea'xn to ojpointlofjylo utilization, andgneatmg sind body of! liquid-by; directing said productsfof jcombustionfthrouzh'fl f vin sgid storage zone; Y v Y a. passagewayV subme'ifgedinthe liquid owne method as@claimedy 1n neming iiireifz151l `rin` the supply of Vsaid yaporsto be'v burned .hij

said firstnstream i's'automatically controlled by?V the` pxssure lconditi:is eidsting in said 1 storage zone.

JMEs WODWRD e 270 Y 

